In the 1978 NHL Entry Draft, Tambellini was chosen 15th overall by the New York Islanders. He would spend two years with New York, winning a Stanley Cup with them in the 1980 season. Despite this cup victory, he would be traded late in the next season to the Colorado Rockies. He stayed with Colorado for two seasons, including their first season as the New Jersey Devils as the franchise was relocated in 1982. After the 1982–83 season, Steve was traded to the Calgary Flames. He would remain there for two seasons before signing on as a free agent with the Vancouver Canucks, where he would round out his NHL career.
He would go on to play a minor amount of time in both the Swiss Hockey League and the Austrian Hockey League.
In 2002, he was the Director of Player Personnel for the gold medal winning Canadian Olympic Men's Ice Hockey Team at the 2002 Winter Olympics. He would be rewarded again, being named the Director of Player Personnel for both the 2003 World Junior Ice Hockey Championships as well as the 2004 World Cup of Hockey, in both of which he would see his team win gold.
In the 2003 NHL Entry Draft, his oldest son, Jeff Tambellini, was drafted 27th overall by the Los Angeles Kings. Jeff now plays for the team that drafted his father, the New York Islanders.
In 2004, he was inducted into the British Columbia Hockey Hall of Fame.
On July 31, 2008 he was named General Manager of the Edmonton Oilers after the Oilers promoted Kevin Lowe to President of Hockey Operations .
| Regular Season | Playoffs | |||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Season | Team | League | GP | G | A | Pts | PIM | GP | G | A | Pts | PIM | ||
| 1975–76 | Lethbridge Broncos | WCHL | 72 | 38 | 59 | 97 | 42 | -- | -- | -- | -- | -- | ||
| 1976–77 | Lethbridge Broncos | WCHL | 55 | 42 | 42 | 84 | 23 | -- | -- | -- | -- | -- | ||
| 1977–78 | Lethbridge Broncos | WCHL | 66 | 75 | 80 | 155 | 32 | -- | -- | -- | -- | -- | ||
| 1976–77 | Fort Worth Texans | CHL | 73 | 25 | 27 | 52 | 32 | 5 | 0 | 1 | 1 | 0 | ||
| 1978–79 | New York Islanders | NHL | 1 | 0 | 0 | 0 | 0 | -- | -- | -- | -- | -- | ||
| 1979–80 | New York Islanders | NHL | 45 | 5 | 8 | 13 | 4 | -- | -- | -- | -- | -- | ||
| 1980–81 | New York Islanders | NHL | 61 | 19 | 17 | 36 | 17 | -- | -- | -- | -- | -- | ||
| 1980–81 | Colorado Rockies | NHL | 13 | 6 | 12 | 18 | 2 | -- | -- | -- | -- | -- | ||
| 1981–82 | Colorado Rockies | NHL | 79 | 29 | 30 | 59 | 14 | -- | -- | -- | -- | -- | ||
| 1982–83 | New Jersey Devils | NHL | 73 | 25 | 18 | 43 | 14 | -- | -- | -- | -- | -- | ||
| 1983–84 | Calgary Flames | NHL | 73 | 15 | 10 | 25 | 16 | 2 | 0 | 1 | 1 | 0 | ||
| 1984–85 | Moncton Golden Flames | AHL | 7 | 2 | 5 | 7 | 0 | -- | -- | -- | -- | -- | ||
| 1984–85 | Calgary Flames | NHL | 47 | 19 | 10 | 29 | 4 | -- | -- | -- | -- | -- | ||
| 1985–86 | Vancouver Canucks | NHL | 48 | 15 | 15 | 30 | 12 | -- | -- | -- | -- | -- | ||
| 1986–87 | Vancouver Canucks | NHL | 72 | 16 | 20 | 36 | 14 | -- | -- | -- | -- | -- | ||
| 1987–88 | Canadian Nation Team | Intl | 10 | 2 | 3 | 5 | 2 | -- | -- | -- | -- | -- | ||
| 1987–88 | Vancouver Canucks | NHL | 41 | 11 | 10 | 21 | 8 | -- | -- | -- | -- | -- | ||
| 1987–88 | Villach VSV | Aust | 36 | 44 | 37 | 81 | 34 | -- | -- | -- | -- | -- | ||
| NHL Totals | 553 | 160 | 150 | 310 | 105 | 2 | 0 | 1 | 1 | 0 | ||||